1. Field of the Invention
The present invention relates to a touch position detecting device, a method of detecting a touch position, and a touch screen display device having the touch position detecting device. More particularly, the present invention relates to a touch position detecting device facilitating detection of a touch position, a method of detecting a touch position, and a touch screen display device having the touch position detecting device.
2. Description of the Related Art
Generally, a touch screen panel is an inputting device disposed on a liquid crystal display (“LCD”) panel in order to input data by a finger or a physical object such as a pen. The touch screen panel includes a first substrate, a second substrate that is spaced apart from the first substrate, a first transparent electrode, and a second transparent electrode formed on the first substrate and the second substrate such that the first and second transparent electrodes face each other.
An LCD device and the touch screen panel are combined through an adhesive, so that an empty gap is created between the touch screen panel and the LCD panel. Therefore, an air gap or the adhesive, which has different refractivity from that of the LCD device and/or the touch screen panel, is disposed between the LCD panel and the touch panel device, thereby deteriorating optical properties of the LCD device.
In order to solve the above-mentioned problem, a touch screen panel has been integrated with an LCD panel by optical sensors. Hereinafter, an LCD panel having the touch screen panel integrated therewith is referred to as a “touch screen LCD panel”.
When the touch screen panel employs optical sensors including an amorphous silicon/polysilicon a-Si/Poly-Si thin-film transistor (“TFT”), etc., touch positions within the touch screen panel are measured by processing sensing data provided from the optical sensors. In view of the signal processing and hardware structure, there are some drawbacks.
First, the sensing data is non-uniform, and includes ripple noise to some degree. Additionally, the sensing data may interfere with an image data signal to create noise, thereby lowering a signal-to-noise ratio (“SNR”), and making exact detection of the touch position difficult.
Second, since a process for the sensing data is performed within one frame interval (1H= 1/60 Hz), the integrated LCD touch panel necessarily detects one touch position within 13 ms, supposing a duration margin of 20%. For example, a 200 ppi Quarter Quarter Video Graphics Array (“QQVGA”) display device having 160×120 touch sensors is required to process 160×120 sensing data within 13 ms. Thus, the panel has a somewhat heavy process load.
Third, much time is consumed when the sensing data is processed by using a segment method and a pre-processing method, which include a smoothing filter (low-pass filter), a sharpening filter (high-pass filter), an additional image transferring process, and a mapping process for transferred images.